1. Field of the Inventive Concept
The present inventive concept relates to nonvolatile memory devices, and, more particularly, to nonvolatile memory devices that use a variable resistive element and fabricating methods thereof.
2. Description of the Related Art
In general, examples of nonvolatile memory devices that use a resistance material include a resistive Random Access Memory (RRAM), a phase change RAM (PRAM), a magnetic RAM (MRAM), and the like. While a dynamic RAM (DRAM) or a flash memory stores data using an electric charge, a nonvolatile memory device that uses a resistance material stores data using a change in resistance of a variable resistive material (RRAM), a change in state of a phase change material (PRAM), such as a chalcogenide alloy, and a change in resistance of a magnetic tunnel junction (MTJ) thin film due to a magnetization state of a ferromagnetic substance (MRAM).
In a phase-change memory cell, for example, when a phase change material is heated and then cooled, its state rapidly changes into a crystalline state or an amorphous state. The phase change material in the crystalline state has low resistance and phase change material in the amorphous state has high resistance. Thus, the crystalline state is referred to as a set state and stores a data value “0” defined as set data or data “0” while the amorphous state is referred to as a reset state and stores a data value “1” defined as reset data or data “1.”